(a) Field of the Invention
The present invention relates to a multiple-purpose foldable frame, and more particularly, to one that the posts of the frame when stretching out are further supported by reinforcement tubes and support tubes so to bear heavier load.
(b) Description of the Prior Art
As illustrated in FIG. 8 of the accompanying drawings, a conventional support structure essentially comprises four posts (7) each being retractable for a certain range, and a pair of connection rods (8), crossing over each other at their center points, is connected to two abutted posts (7). Each connection rod (8) is pivoted to the upper end of a respective post (7) and to the lower end of another post (7) to constitute a rectangular frame. Each post (7) is composed of an inner tube (71) inserted into an outer tube (72) for the post (7) to become retractable. An L-shaped pivot holder (9) is each provided to the upper end and the lower end of each post (7). A hole is provided at the center of each pivot holder (9) to receive insertion of the post (7), and two recesses are respectively provided on both side ends on the pivot holder (9) to pivot respectively the upper end and the lower end from the cross connection rods (8) so to allow them to stretch out. The length of each post (7) is vertically reduced as the cross connection rods (8) stretch out to immediately form a rectangular frame ready for covering up with canvas or bag to become a foldable desk or bed, and garbage bag whichever requires a foldable frame to stretch out.
However, the frame of the prior art could barely hold heavier load from the canvas or bag fixed on the top of the frame. The post (7) is vulnerable to be curved and deformed, and in gravid circumstances, the entire frame may accidentally collapse to threaten safe use of the frame.